Archive Shuttle SourceOne module may log Error: Sender is null (4293618)

Overview
You may encounter the error Sender is null! during a migration from Source One archive manager.

See the example below:

 2018-03-16 13:23:01Z|7000|S1 server| 18|ERROR| SaveItems|Item export failed! Item Identifier: [201610%20161031234567%59B810UFD4959UIHILUHB2B10D160A5400], Bucket Id: [-3515994502517958093], Mapping Id: [1], Routing Id: [12345678]. Error msg: Timefinity.Messaging.Library.Journal.JournalReconstructionException: Sender is null!
 at Timefinity.Messaging.Library.Journal.JournalMessageBodyGenerator2007.GetBody(IJournalEnvelope envelope)
 at Timefinity.Messaging.Library.Journal.JournalMessageBodyGenerator.GetBody(IJournalEnvelope envelope)
 at Timefinity.Messaging.Library.Journal.JournalReconstructor.Reconstruct(Message p2, IJournalEnvelope envelope, Boolean ignoreMissingTransportHeaders)
 at Timefinity.ConnectorFramework.SourceOne.SourceOneJournalReconstructor.CreateEnvelope(Message message, IList`1 databaseRecipients

Explanation
During the reconstruction of a P1 journal message header, Archive Shuttle is trying to reconstruct the sender SMTP address. If the sender address is NULL, the export will fail.
Each target system has requirements for the ingestion of a message. If the message in the source does not contain the properties to meet these requirements, importing those messages fails.